1. Field of the Invention
The invention relates to a two part epoxy resin adhesive formulation.
2. Description of Other Relevant Materials in the Field
Curing epoxy resins with amino containing compounds to form adhesives is known in the art.
U.S. Pat. No. 4,187,367 to H.G. Waddill teaches an epoxy resin adhesive comprising an epoxy resin, a polyether diureide having terminal ureido or monosubstituted ureido groups and having a molecular weight of about 2000 to 3000 and an aminoalkylene derivative of polyoxyalkylenepolyamine.
U.S. Pat. No. 4,051,195 to W. F. McWhorter teaches curable epoxy resin compositions comprising (1) a blend of an epoxide resin and a polyacrylate or polymethacrylate ester of a polyol wherein the ester contains more than one terminal acrylate or methacrylate and (2) an aliphatic polyamine curing agent. The weight ratio of epoxide resin:ester is 100:5 to 100:100. The aliphatic polyamine is incorporated into the resin composition in a specified amount. The epoxy resin compositions are said to cure rapidly even at low temperature and are useful as coatings and adhesives.
U.S. Pat. No. 4,528,345 to H. G. Waddill teaches a method for making weather-resistant epoxy coatings. The method comprises prereacting a cycloaliphatic diepoxide resin with aminoethylpiperazine or a mixture of aminoethylpiperazine and polyoxyalkylenepolyamine in an amount which is balanced to give the maximum level of primary amine reaction without yielding an excessively viscous reaction product. The prereacted product is reacted with a curing amount of a polyoxyalkylene polyamine and an accelerator.
U.S. Pat. No. 3,875,072 to H. G. Waddill teaches an accelerator for curing epoxy resins. The accelerator comprises piperazine and an alkanolamine in a weight ratio of 1:8 to 1:1.
U.S. Pat. No. 4,195,153 to H. G. Waddill teaches a non-crystallizing accelerator for curing curing epoxy resins. The accelerator comprises a mixture of N-aminoethylpiperazine and triethanolamine.
U.S. Pat. No. 4,189,564 to H. G. Waddill teaches a non-crystallizing accelerator for curing epoxy resins. The accelerator comprises a mixture of piperazine, N-aminoethylpiperazine and triethanolamine. The product comprising 65 to 80 wt% triethanolamine, 10 to 20 wt% piperazine and 5 to 10 wt% N-aminoethylpiperazine is sold commercially as Accelerator 399 by Texaco Chemical Co. The accelerator is said to be synergistic for accelerating the curing of a polyglycidyl ether of a polyhydric phenol cured with a polyoxyalkylene polyamine at ambient or elevated temperatures. Such amines include polyoxypropylene diamines of the formula: EQU NH.sub.2 CH(CH.sub.3)CH.sub.2 [OCH.sub.2 CH(CH.sub.3)].sub.x NH.sub.2
wherein x ranges from 2 to 40.
These diamines may be synthesized according to U.S. Pat. No. 3,654,370 to E. L. Yeakey which teaches a method comprising a nickel, copper and chromium catalyst for aminating polyols. These diamines were originally taught in U.S. Pat. No. 3,462,393 to Legler.
U.S. Pat. No. 3,496,138 to R. F. Sellers and C. F. Pitt teaches curing diepoxides with polyglycol diamines. Suitable glycol precursors to these diamines include ethylene glycol, diethylene glycol and polyethylene glycol.